Fluidized bed heat treatment apparatus



July 9, 1968 R. F. J. MORGAN 3,391,915

FLUIDIZED BED HEAT TREATMENT APPARATUS Filed Feb. 27, 1964 INVENTOR ROBERT FJ. MORGAN IS ATTORNEY United States Patent 3,391,915 FLUIDIZED BED HEAT TREATMENT APPARATUS Robert Frederic Jenkin Morgan, Sheifield, England, as-

signor to Davy and United Engineering Company, Limited, Yorkshire, England Filed Feb. 27, 1964, Ser. No. 347,736 Claims priority, application Great Britain, May 2, 1963, 17,356/63 6 Claims. (Cl. 266-3) This invention relates to annealing of elongate metallic material. The invention is particularly applicable to the annealing of ferrous strip in which the material is rapidly raised to a sub-critical annealing temperature (approximately 700 C.), a super-critical annealing temperature (approximately 800 C.) or a super-critical annealing temperature (approximately 900 C.) and is then rapidly cooled.

In one aspect the invention provides a method of continuously annealing elongate metallic material in which the material is passed in a substantially vertical direction through a series of fluidised beds in succession, the beds being maintained at progressively increasing temperatures.

In another aspect the invention provides apparatus for continuously annealing elongate metallic material comprising a fluidised bed container having a series of contiguous compartments arranged vertically above one another, means for passing the material through the compartments in succession, and means for maintaining fluidised beds in the compartments at progressively increasing temperatures.

The material may thereafter be rapidly cooled by passing it through a liquid metal bath maintained at a relatively low temperature.

An embodiment of annealing line, in accordance with the invention, will now be described, by way of example only, with reference to the accompanying drawing which shows a section through an annealing line.

Referring to the drawing, a refractory lined, steel, fluidised bed container 12, of cylindrical form with its axis vertical, is divided into seven compartments 13 by diffuser plates 14, which also form the basis of the compartments for supporting the bed material. The bed material may be any particulate material, such as sand which can stand the elevated temperatures to which the fluidised beds will be raised and which does not react with the strip 24 to be annealed. Each diffuser plate is formed with a slot 16 to permit passage of the material 24 therethrough. Each diifuser plate is also provided with a plurality of bubble cap jets 17 to which fiuidising gas is supplied from main conduits 18 via branch conduits 19. Each compartment is provided with a gas exhaust vent 20, connected to a dust separator (not shown). The fluidising gas may be nitrogen or any gas which does not react with the strip being annealed.

Electric heaters 21 are arranged in each compartment adjacent the strip path and arranged to be immersed by the particulate material when in a fluidised state. In operation the heaters are controlled so that the compartments are maintained at different increasingly elevated temperatures along the path of the material. For example the lowest compartment may be maintained at a temperature which will heat the strip to about 200 C., while the uppermost compartment may be maintained at a temperature which will heat the strip to about 800 C., or for a super-critical anneal to around 900 C. The intermediate compartments are maintained at tem- 3,391,915 Patented July 9, 1968 peratures gradually increasing from the bottom to the top of the container 12.

Slots 22, 23 are provided at the top and bottom respectively of the container 12 for entry :and exit of the material 24. The lower portion 25 of the container 12 has a guide roll 26 for guiding the material 24 entering through the slot 22 into the compartments 13. Gas jets 27 are arranged to blow any particulate material falling from the lowest compartment 13 clear of the guide roll 26 and the strip. The portion 25 is open to an outlet duct 28 in which falling particulate material is collected and passed to an ejector pump 29 from where it is pneumatically transported by a gas stream issuing from a pipe 30 to a cyclone separator 31 having a gas outlet 32 and a particulate material outlet 33 leading to the uppermost compartment 13.

At the exit end of the container 12 is :a further closed container 35 containing a lead-bismuth bat-h 36. In operation the lead-bismuth bath is maintained at a comparatively cold temperature, for example 200 C. This may be achieved by circulating the liquid lead-bismuth between a bath and cooling means (not shown) via the pipes 41. In an alternative arrangement the lead-bismuth may be brought into heat exchange relationship with the fluidised beds. In this way the otherwise waste heat in the lead-bismuth is used to heat the fluidised beds. Above the surface of the lead-bismuth the container 37 is filled with an inert gas such as nitrogen. At the exit of the container 12 guide rolls 34 are provided to reverse the direction of the strip leaving the container, and guide rolls 38 are provided in the bath to guide the material through the bath. Pinch rolls 39, 40 are provided at the exit of the container 25 to form a seal.

In operation strip 24 enters through the slot 22 passes round the guide roll 26, through the chambers 13 in which it is heated, over the guide rolls 34, is quenched in the liquid bath 36, and emerges through the pinch rolls 39, 40.

I claim:

1. Apparatus for annealing elongate metallic material comprising a fluidised bed container having a series of contiguous compartments arranged vertically above one another, means for passing the material vertically through the compartments in succession, and means for maintaining fluidised beds in the compartments at progressively increasing temperatures.

2. Apparatus according to claim 1 in which the container is divided into compartments by diffuser plates each formed with a slot for passage of the elongated material.

3. Apparatus according to claim 2 in which each diffuser plate carries a plurality of bubble cap jets, and including means for applying fiuidising gas to the jets,

4. Apparatus according to claim 3 in which the means for maintaining the fluidised beds at progressively increasing temperatures comprise heaters immersed in the beds.

5. Apparatus according to any one of claim 1 in which the means for maintaining the beds at progressively increasing temper-atures are arranged to maintain the beds at temperatures such as to heat the material through the range ZOO-800 C.

6. Apparatus according to any one of claim 1 including a lead-bismuth bath maintained at a temperature of around 200 C. and arranged to receive the material following its issuance from the fluidised bed container.

(References on following page) References Cited UNITED STATES PATENTS Miess 2663 X Jenkins et a1 2663 X 5 Sturgeon 266-3 X Brooks 118-405 X Ramsay 118405 X '4 I OTHER REFERENCES Chemical :and Process Engineering, Developments in Applications of Fluidisation, March 1963, pp. 127-131, TPI. C368 (copy in group 322).

J. SPENCER OVERHOLSER, Il-imary Examiner.

R. S. ANNEAR, Assistant Examiner. 

1. APPARATUS FOR ANNEALING ELONGATE METALLIC MATERIAL COMPRISING A FLUIDISED BED CONTAINER HAVING A SERIES OF CONTIGUOUS COMPARTMENTS ARRANGED VERTICALLY ABOVE ONE ANOTHER, MEANS FOR PASSING THE MATERIAL VERTICALLY THROUGH THE COMPARTMENTS IN SUCCESSION, AND MEANS FOR MAINTAINING FLUIDISED BEDS IN THE COMPARTMENTS AT PROGRESSIVELY INCREASING TEMPERATURES. 